International Center for Elementary Particle Physics, The University of Tokyo

School of Science, The University of Tokyo

Summary of Presentations

The MEG II, an international collaboration with institutes from Japan, Switzerland, Italy, the United States, the United Kingdom, and other countries where The University of Tokyo, High Energy Accelerator Research Organization (KEK), and Kobe University play a leading role, started the data-taking to search for the rare muon decay, mu->e+gamma at the end of September 2021(Fig. 1, 2). The experiment utilizes innovative detectors and the world's most intense muon beam at the Paul Scherrer Institute (PSI) in Switzerland. The result from the search for mu->e+gamma conducted using the first data acquired in 2021 is presented. The mu->e+gamma has not been discovered in this data, but instead, together with the result of the previous MEG experiment, a most stringent limit on the existence of the mu->e+gamma (1 in 3 trillion times). This research is an attempt to unravel the Grand Unification of elementary particles at the birth of the Universe. The MEG II experiment continues the data acquisition and is expected to greatly exceed the search sensitivity of the MEG experiment with the data already obtained in 2022. The data acquisition will continue until 2026, eventually achieving a search sensitivity about 10 times higher than that of the MEG experiment (1 in 17 trillion times), and through the search and discovery of the mu->e+gamma, the Grand Unification of elementary particles at the birth of the universe will be verified.

Figure 1: MEG II experimental apparatus

 

Figure 2: Normal decay of a muon (left) and mu->e+gamma predicted by the Grand Unified Theory (right). 
In mu->e+gamma, very heavy unknown new particles such as supersymmetric particles contribute.

 

For more information, please visit the website of the International Center for Elementary Particle Physics, The University of Tokyo.